My guess is that the bottom line is that you can only access 5.1 and 7.1 if you have a usb port that can be used to send the encoded signal. In most cases this means a Mac or pc as source. Other options would be a device which can extract a surround signal from a different method (HDMI, optical, whatever) and convert it to a compatible signal but since the headphones effectively become an audio device for the computer, this may not be possible due to use of software and drivers.
This is guesswork on my part though, based on this thread. Happy to be corrected!
Thanks for the reply. I was afraid of that. I'm hoping you can be "happy to be corrected"
I don't really game per say and I'd love to pick up a pair of these for later night movie watching. It seems like it would be a waste of money to pick these up as I really don't need any more HP's other then something for home theater.